2009 Volume 7 Pages 601-605
Interactions between self-assembled monolayers (SAMs) with various non-dissociative terminal groups were explored with an atomic force microscope (AFM). In the pure water, hydrophobic CH3-terminated SAMs showed long-range repulsion (> 50 nm) indicating that hydroxide ions are concentrated at the water-SAM interface. On the other hand, hydrophilic OH-terminated SAMs exhibited only short-range attraction and no repulsion originated from ions accumulated at the SAM-water interface. The interaction between SAMs of oligo(ethylene glycol)-terminated alkanethiols strongly depend on the substrate (Au and Ag). That is, the hydroxide ions were concentrated near the Au-supported SAM, whereas no accumulation of the ions near the Ag-supported SAM was observed. Our results demonstrated that not only the terminal groups but also the density of the molecules constituting the SAM critically govern the redistributions of ions at the SAM-water interfaces. [DOI: 10.1380/ejssnt.2009.601]
